Re-allow an untyped literal as the test expression of a CASE, ie

CASE 'a' WHEN 'a' THEN 1 ELSE 2 END.  This worked in 7.4 and before
but had been broken due to premature freezing of the type of the test
expression.  Per gripe from GÄbor SzÃcs.

diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index c00dc72..6676ae0 100644 (file)
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.178 2004/12/31 22:00:27 pgsql Exp $
+ *       $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.179 2005/01/12 17:32:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -646,10 +646,21 @@ transformExpr(ParseState *pstate, Node *expr)
 
                                /* transform the test expression, if any */
                                arg = transformExpr(pstate, (Node *) c->arg);
-                               newc->arg = (Expr *) arg;
+
                                /* generate placeholder for test expression */
                                if (arg)
                                {
+                                       /*
+                                        * If test expression is an untyped literal, force it to
+                                        * text.  We have to do something now because we won't be
+                                        * able to do this coercion on the placeholder.  This is
+                                        * not as flexible as what was done in 7.4 and before,
+                                        * but it's good enough to handle the sort of silly
+                                        * coding commonly seen.
+                                        */
+                                       if (exprType(arg) == UNKNOWNOID)
+                                               arg = coerce_to_common_type(pstate, arg,
+                                                                                                       TEXTOID, "CASE");
                                        placeholder = makeNode(CaseTestExpr);
                                        placeholder->typeId = exprType(arg);
                                        placeholder->typeMod = exprTypmod(arg);
@@ -657,6 +668,8 @@ transformExpr(ParseState *pstate, Node *expr)
                                else
                                        placeholder = NULL;
 
+                               newc->arg = (Expr *) arg;
+
                                /* transform the list of arguments */
                                newargs = NIL;
                                typeids = NIL;